1. Field
Embodiments of the present application are generally directed to communication networks, and more specifically, to power control schemes in heterogeneous communication networks.
2. Related Art
The Long Term Evolution-Advanced (LTE-A) network is designed to improve the spectral efficiency by reducing cell size via heterogeneous deployment of a diverse set of base stations (BS). In a heterogeneous cellular network, the macro BSs are deployed in a regular and planned manner with a high transmit power (e.g., 46 dBm), and the overlaid pico BSs are deployed in areas with poor coverage (e.g., the edge of a macro cell) with relatively low transmit power (e.g., 30 dBm). The overlaid BS deployment may improve the coverage and may provide capacity gain by increasing spatial reuse of the spectrum.
In LTE-A Release 10 (Rel-10), the macro BSs can mute certain subframes, which are known as almost blank subframes (ABS), to reduce the interference to the pico user equipment (UE). In an ABS, most resource elements (RE) are blank and only a small amount of REs carry some system information (e.g., the cell-specific reference signals and synchronization signals). The pico UEs may thereby suffer less interference and may achieve a higher data rate when the macro BSs transmit ABSs.
In LTE-A systems, the radio resource is divided into REs and physical resource blocks (PRB). FIG. 1 illustrates an example structure of a Long Term Evolution/Long Term Evolution Advanced (LTE/LTE-A) subframe.
In FIG. 1, the structure of an LTE/LTE-A subframe is shown in time and frequency domain. Each subframe is divided into two time slots, with each time slot containing 7 orthogonal frequency-division multiplexing (OFDM) symbols (for normal cyclic prefix length). Each grid with an OFDM symbol length and a subcarrier bandwidth is called an RE. A PRB has the same length as a time slot in time domain and spans 12 subcarriers in frequency domain.
The LTE-A network is a heterogeneous network, where macro and pico BSs coexist which may improve spectral efficiency per unit area. However, in such a macro-pico deployment, the pico UEs, especially those in the cell edge, tend to suffer strong interference from their neighboring macro BSs.